The present invention relates to a gas insulated switching apparatus and more particulary, to a gas insulated switching apparatus with a metering outfit (combined voltage-current transformer) (hereinafter referred to as an "MOF") used for a power receiving system.
A gas insulated switching apparatus for a power receiving system has an MOF for measuring the electric energy consumed.
A gas insulated switching apparatus of this type is well-known as disclosed, for example, in Japanese Laid-Open Utility Model Publication No. 51-7615. FIG. 6 is a circuit diagram showing a gas insulated switching apparatus comprising a gas tube path having a plurality of gas sections filled with a high-insulation gas.
This circuit is called a "two-line two-bank system" and is supplied with power from two systems of transmission lines 1a and 1b. The power transmission lines 1a and 1b are led into a gas insulated switching apparatus through bushings 2a and 2b, and is connected by a bus 6 through disconnectors 3a and 3b, circuit breakers 4a and 4b, and disconnectors 5a and 5b. The same gas section where the bus 6 is arranged has also a bus 8, and the MOF 7 is connected between the buses 6 and 8. Further, the bus 8 is led out by bushings 13a and 13b through an insulating spacer 10, and disconnectors 11a and 11b and is connected to transformers 12a and 12b.
Since the MOF 7 is a low impedance device, the potential difference between the buses 6 and 8 is approximately several volts. It is, therefore, possible to arrange the buses 6 and 8 in the same gas section. As a result, the switching apparatus has been reduced in size by using conductors of coaxial cylinders or semicircular split conductors.
FIG. 7 is an enlarged view showing the essential parts of the switching apparatus of FIG. 6. This diagram shows parts near the buses 6 and 8 and the disconnector 11a.
A bus casing 15 sealed with an insulating gas has fixed a conductor 21 connected to the disconnector 5a of FIG. 6. This conductor 21 is connected electrically to an inner conductor 22 of coaxially cylindrical double conductors. The inner conductor 22 is electrically insulated from an outer conductor 23 with an insulating member 29 between the conductors 22 and 23, and is connected to an end of the disconnector 5b in FIG. 6. The ends of the outer conductor 22, on the other hand, are connected to the disconnectors 11a and 11b in FIG. 6. The MOF 7 is inserted between the conductors 22 and 23. The inner conductor 22 makes up the bus 6, and the outer conductor 23 the bus 8. The outer conductor 23 is electrically connected to a central conductor of an insulating spacer 16 through a collector 30 branching downward. This insulating spacer 16 defines a gas section 31 on the double conductors side and a gas section 27 on the disconnector side. A collector 24 on the needle (moving element) side of the disconnector 11a is fixed on the insulating spacer 16, and a stator 25 is fixed on an insulating spacer 17. The collector 24 and the stator 25 are connected by way of a needle 26.
In the configuration of FIG. 7, as compared with that developed before the double-conductor construction allows the buses 6 and 8 to be arranged in the same gas section 31, thereby reducing the size of the switching apparatus.
The conventional apparatus, however, with the double conductors arranged between exclusive buses for a low impedance device, has its own limitation in size reduction.